joomla/joomla-cms — pull request #2336 by okonomiyaki3000 (2013-10-25 05:37:12+00:00)
Title: The option rule properly validates whether there are one or multiple values.

2.5.x fix for this: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32422&start=0